haloalkanes and haloarenes neet questions
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Haloalkanes And Haloarenes Neet Questions 1. Which of the following is a vinylic halide?
a) CH2=CHCHCl2
b) CH3CHClCH3
c) (CH3)2C=CHCH2Cl
d) CH3CH=CClCH2CH3
Answer: d
2. The compound C6H5F is an example of a ________ halide.
a) allylic
b) benzylic
c) vinylic
d) aryl
Answer: d
3. Monohalo, dihalo, trihalo and tetrahalo are types of haloalkanes and haloarenes based on the ______
a) type of halogen atom
b) number of halogen atoms
c) nature of carbon atom
d) hybridisation of C atom to which halogen is bonded
Answer: b
4. A monohaloarene is an example of a/an __________
a) aliphatic halogen compound
b) aromatic halogen compound
c) alkyl halide
d) side chain substituted aryl halide
Answer: b
5. What is the general formula for haloalkanes? (X=halogen atom, n = 1, 2, 3…)
a) CnH2nX
b) CnH2n+1X
c) CnH2n-1X
d) CnH2n-3X
Answer: b
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6. In the common naming system, the prefix sym- is used for haloarenes with _____ halogen atoms.
a) 1
b) 2
c) 3
d) 4
Answer: c
7. How many carbon atoms does Isobutyl chloride have in its parent carbon chain?
a) 2
b) 3
c) 4
d) 5
Answer: b
8. Identify the correct naming of the compound H3C-CHCl2 from the following?
a) Ethylidene chloride
b) Ethylene dichloride
c) 1,2-Dichloroethane
d) Vic-dichloride
Answer: a
9. Identify the correct common name for CH3CH2CH2CH2Cl.
a) Isobutyl chloride
b) n-Butyl chloride
c) sec-Butyl chloride
d) tert-Butyl chloride
Answer: b
10. What is the IUPAC name for the compound (CH3)3CCH2Cl?
a) 1-Chloro-2,2-dimethylpropane
b) 1-Chloro-2,2,2-trimethylethane
c) 2-Chloromethyl-2-methylpropane
d) 2,2-Dimethly-1-Bromopropane
Answer: a
11. What is the correct IUPAC naming of CHF2CBrClF?
a) 1-Bromo-1-chloro-1,2,2-trifluoroethane
b) 1-Bromo-1-chloro-1,2,2-trifluoroethene
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c) 2-Bromo-2-chloro-1,1,2-trifluoroethane
d) 2-Bromo-2-chloro-1,1,2-trifluoroethene
Answer: a
12. The correct naming of the compound CH≡C-CH=CH-CH3 is __________
a) Pent-3-en-1-yne
b) Pent-2-en-4-yne
c) Pent-3-ene-1-yne
d) Pent-2-ene-4-yne
Answer: a
13. How many isomers does C5H11Br have?
a) 4
b) 6
c) 8
d) 10
Answer: c
14. If the bond length of C-Cl bond in chloromethane is 178pm, what will be the probable bond length of
C-Br bond in bromomethane?
a) 139pm
b) 156pm
c) 178pm
d) 193pm
Answer: d
15. If X and Y are the carbon-halogen bond enthalpies in chloroethane and bromoethane respectively,
what is the relationship between X and Y?
a) X > Y
b) X < Y
c) X = Y
d) X + Y = 0
Answer: b
16. The carbon-halogen bond of an alkyl halide is polarised due to the _________
a) higher electronegativity of halogen atom than carbon
b) higher electronegativity of carbon than halogen atom
c) partial positive charge on halogen atom and a partial negative charge on carbon
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d) tendency of halogen atom to donate electrons
Answer: a
17. The size of the halogen atom _________ as we go down the group in the periodic table.
a) increases
b) decreases
c) remains same
d) increases then decreases
Answer: a
18. Which is the largest halogen atom?
a) Bromine
b) Chlorine
c) Fluorine
d) Iodine
Answer: d
19. The reaction of a primary alcohol with which of the following gives purely a haloalkane?
a) Phosphorus trichloride
b) Phosphorus pentachloride
c) Thionyl chloride
d) Sulphuryl chloride
Answer: c
20. When ethanol reacts with PCl5, it gives three products which include chloroethane and hydrochloric
acid. What is the third product?
a) Phosphorus acid
b) Phosphoric acid
c) Phosphorus trichloride
d) Phosphoryl chloride
Answer: d
21. What do you get by heating a mixture of hexanol and concentrated aqueous hydrogen chloride?
a) Cyclochlorohexane
b) Chlorohexane
c) Phosphorus acid
d) No reaction
Answer: b
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22. Iodoalkanes can be obtained by heating alcohols with potassium iodide in __________
a) hypophosphrus acid
b) phosphorus acid
c) phosphoric acid
d) hypophosphoric acid
Answer: c
23. The following reaction to form haloalkanes is an example of which type of reaction?
Propane + Cl2 (in the presence of UV light) = 1-Chloropropane + 2-Chloropropane
a) Free radical substitution
b) Halogen exchange
c) Finkelstein reaction
d) Swarts reaction
Answer: a
24. How many monohaloalkane isomers can be formed on the free radical bromination of
(CH3)2CHCH2CH3?
a) 2
b) 3
c) 4
d) 5
Answer: c
25. When propene reacts with HBr, two products are formed out of which one is predominates the other.
Identify the minor product.
a) 1-Bromopropane
b) 2-Bromopropane
c) 1-Bromobutane
d) 2-Bromobutane
Answer: a
26. Which of the following is incorrect with regard to the reaction between C2H4 and Cl2 in CCl4?
a) It results in the formation of a vicinal dihalide
b) It results in the breaking of the C-C double bond
c) It results in the formation of a colourless compound
d) It results in the discharge of a reddish-brown colour
Answer: d
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27. The Finkelstein reaction takes place in what medium?
a) Concentrated HCl
b) Concentrated H2SO4
c) Dry acetone
d) Water
Answer: c
28. What is the correct order of reactivity of alcohols with a given haloacid?
a) 1° > 2° > 3°
b) 3° > 2° > 1°
c) 1° > 3° > 2°
d) 2° > 1° > 3°
Answer: b
29. What is the correct order of reactivity of the following haloacids with a given alcohol?
a) HCl > HBr > HI
b) HI > HBr > HCl
c) HBr > HCl > HI
d) HI > HCl > HBr
Answer: b
30. What is the catalyst in the reaction of a primary alcohol with HCl to obtain a chloroalkane?
a) anhydrous ZnCl2
b) concentrated H2SO4
c) red phosphorous
d) pyridine
Answer: a
1. The ortho and para isomers formed by electrophilic substitution of arenes can be easily separated due
to the large difference in their ________
a) densities
b) solubilities
c) melting points
d) boiling points
Answer: c
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2. In the iodination of benzene, which compound causes the reduction of iodobenzene back to benzene?
a) Iodic acid
b) Hydrogen iodide
c) Nitric acid
d) Mercuric oxide
Answer: b
3. What is the most suitable temperature for the formation of a diazonium salt from aniline?
a) 0°C
b) 18°C
c) 37°C
d) 60°C
Answer: a
4. What is the by-product formed along with the haloarene at the end of Sandmeyer’s reaction?
a) H2O
b) HCl
c) NO2
d) N2
Answer: d
5. Which of the following is a reagent used in the preparation of benzene diazonium chloride from
aniline?
a) Sodium hydroxide
b) Sodium chloride
c) Sodium nitrite
d) Sodium nitrate
Answer: c
6. What happens when a solution of benzene diazonium bromide and an aqueous solution potassium
iodide are shaken together?
a) Iodobenzene is formed
b) Bromobenzene is formed
c) A dihaloarene is formed
d) No reaction
Answer: a
7. Which of the following cannot be a catalyst in the electrophilic substitution of arenes?
a) FeCl3
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b) FeBr3
c) NH3
d) AlCl3
Answer: c
8. Which of the following are the most suitable conditions for electrophilic substitution of arenes?
a) UV light and heat
b) Cold and dark
c) 40oC temperature and dark
d) Room temperature and sunlight
Answer: c
9. When excess chlorine is used in electrophilic substitution of toluene, which of the following
dichloroarenes are formed?
a) ortho and meta
b) ortho and para
c) meta and para
d) ortho, meta and para
Answer: b
10. Which of the following haloalkanes exist as liquids at room temperature?
a) Methyl chloride
b) Methyl bromide
c) Ethyl chloride
d) Propyl bromide
Answer: d
11. For a particular alkyl group R, what is the correct order of boiling points of the following compounds?
a) RBr > RCl > RF
b) RF > RCl > RBr
c) RCl > RBr > RF
d) RF > RBr > RCl
Answer: a
12. What is the correct relation between boiling points of the following alkyl iodides, where R=methyl,
R’=ethyl and R”=propyl?
a) RI > R’I > R”I
b) R”I > R’I > RI
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c) RI = R’I = R”I
d) R”I = R’I > RI
Answer: b
13. If chloromethane has a boiling point of 250K, what will be the probable boiling point of methane?
a) 110K
b) 250K
c) 275K
d) 315K
Answer: a
14. Which of the following has the highest boiling point?
a) Chloromethane
b) Dichloromethane
c) Trichloromethane
d) Tetrachloromethane
Answer: d
15. The boiling points of isomeric alkyl halides _______ with increase in branching.
a) increase
b) decrease
c) remains same
d) cannot be determined
Answer: b
16. What is the correct order of boiling of isomeric dichlorobenzenes?
a) ortho>meta>para
b) para>meta>ortho
c) para>ortho>meta
d) meta>ortho>para
Answer: c
17. What is the value of diploe moment of p-Dichlorobenzene?
a) 0
b) 1
c) >1
d) <1
Answer: a
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18. Calculate the dipole moment of m-Dichlorobenzene if the dipole moments of C-Cl bonds are 1.72D.
a) 0
b) 1.72D
c) 2.54D
d) 2.98D
Answer: b
19. Which of the following has the highest density?
a) CH3Cl
b) CH2Cl2
c) CHCl3
d) CCl4
Answer: d
20. Which of the following has the lowest boiling point?
a) Bromomethane
b) Bromoform
c) Chloromethane
d) Dibromomethane
Answer: c
21. The reaction that takes place when an electron rich species stronger than the halide approaches the
partially positive carbon atom of a haloalkane and forms a new bond with the carbon atom and in the
process displacing the halogen is called a ________ reaction.
a) displacement
b) electrophilic substitution
c) nucleophilic substitution
d) elimination
Answer: c
22. What will be the class of the nucleophilic substitution product when sodium hydroxide reacts with
chloroethane?
a) Alkane
b) Alcohol
c) Amine
d) Ether
Answer: b
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23. Identify the nucleophile in the substitution reaction between water and bromopropane.
a) Br–
b) H+
c) OH–
d) H2O
Answer: d
24. What is the class of the substitution product of the reaction between LiAlH4 and an alkyl halide?
a) Haloalkane
b) Hydrocarbon
c) Nitroalkane
d) Alkyl nitrite
Answer: b
25. Which of the followings reagents forms an isonitrile when reacted with an alkyl halide?
a) KCN
b) AgCN
c) KNO2
d) AgNO2
Answer: b
26. Which of the following is not an ambident nucleophile?
a) Hydroxide
b) Thiocyanate
c) Cyanide
d) Nitrite
Answer: a
27. Identify the nucleophile that gives a primary amine and hydrogen bromide on reaction with
bromoethane.
a) NH2
b) NH3
c) H2O
d) H
Answer: b
28. Which of the following statements in incorrect regarding SN2 mechanisms?
a) The rate of the reaction depends on the concentration of both reactants
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b) The complete mechanism takes place in a single step
c) The transition state is stable
d) There is inversion of configuration
Answer: c
29. The reaction between chloroethane and potassium hydroxide is a _______ order reaction.
a) zero
b) first
c) second
d) third
Answer: c
30. A haloalkane is known to have an SN2 reaction rate 30 times faster than that of ethyl bromide.
Identify the haloalkane.
a) Methyl bromide
b) Isopropyl bromide
c) tert-Butyl bromide
d) neo-Pentyl bromide
Answer: a
1. Which of the following will have the highest reactivity towards SN2 reaction, where R=methyl group?
a) R-F
b) R-Cl
c) R-Br
d) R-I
Answer: d
2. Which of the following statements is correct regarding unimolecular nucleophilic substitution
reactions?
a) It takes place in three steps.
b) The rate of the reaction depends on the concentration of all the reactants.
c) The first step is the slowest and determines the rate of reaction.
d) None of the steps are reversible.
Answer: c
3. As the stability of carbocation formed in the first step of SN1 reaction increases, the rate of the
reaction _________
a) increases
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b) decreases
c) remains same
d) may increase or decrease
Answer: a
4. The SN1 reaction cannot be carried out in which of the following media?
a) Acetic acid
b) Acetone
c) Ethanol
d) Water
Answer: b
5. If a compound does not affect the plane of plane polarised light when passed through it, the
compound is said to be _________
a) optically active
b) optically inactive
c) dextrorotatory
d) laevorotatory
Answer: b
6. Which of the following compounds does not have a stereocenter?
a) Propan-2-ol
b) Butan-2-ol
c) 2-Bromo-1-chlorobutane
d) 2-Bromopentane
Answer: a
7. Which of the following has a chiral carbon atom?
a) 2-Chloro-2-methylpentane
b) 1,1-Dibromoethane
c) Pentan-3-ol
d) 2-Bromopentane
Answer: d
8. What is the chirality of 2-Chlorobutane?
a) Chiral
b) Achiral
c) Superimposable mirror images
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d) Symmetric
Answer: a
9. A chiral compound with an ‘X’ group attached to the stereocenter has been replaced by a ‘Y’ group.
The product obtained rotates the plane of polarised light in the direction opposite to that of the original
compound. Name the process that has taken place.
a) Inversion
b) Retention
c) Racemisation
d) Inversion or retention
Answer: d
10. The process of separation of a racemic mixture into the respective d and l optical isomers is called
__________
a) racemisation
b) resolution
c) inversion
d) retention
Answer: b
11. What will be the effect on the plane of plane polarised light when it passes through a solution of
dlbutan-2-ol?
a) Clockwise rotation
b) Anti-clockwise rotation
c) Zero rotation
d) 180° rotation
Answer: c
12. When (-)-2-bromooctane reacts with potassium hydroxide over an SN2 mechanism, what will be the
product formed?
a) (-)-octan-1-ol
b) (+)-octan-1-ol
c) (-)-octan-2-ol
d) (+)-octan-2-ol
Answer: d
13. The heating of 1-Chlorobutane along with alcoholic KOH results in ________
a) elimination of hydrogen from α-carbon atom
b) elimination of hydrogen from β-carbon atom
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c) elimination of hydrogen from γ-carbon atom
d) no reaction
Answer: b
14. What is the correct order of reactivity of haloalkanes towards β-elimination reactions?
a) 1°>2°>3°
b) 3°>2°>1°
c) 1°>3°>2°
d) 3°>1°>2°
Answer: b
15. How many β-carbon atoms does 2-Bromobutane have?
a) 0
b) 1
c) 2
d) 3
Answer: b
16. Which of the following is the suitable medium for preparing Grignard reagents?
a) Dry acetone
b) Dry ether
c) Concentrated HCl
d) Alcoholic KOH
Answer: b
17. What is formed when ethyl magnesium bromide reacts with water?
a) Grignard reagent
b) Ethane
c) Ethanol
d) Magnesium hydroxide
Answer: b
18. What will be the product of the following reaction?
2CH3CH2Br + 2Na + dry ether = ________
a) Ethane
b) 1-Bromoethane
c) Butane
d) 1-Bromobutane
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Answer: c
19. Compared to haloalkanes, the reactivity of haloarenes towards nucleophilic substitution reactions is
_________
a) low
b) high
c) very high
d) equal
Answer: a
20. The C-Cl bond length in chlorobenzene is less than the C-Cl bond length in chloromethane because of
the ________
a) resonance effect in haloarenes
b) difference in hybridisation of carbon in C-Cl bond
c) instability of phenyl cation
d) possible repulsion between nucleophile and chlorobenzene
Answer: b
21. Which of the following compounds is most easily converted to a phenol when heated with aqueous
NaOH solution?
a) Chlorobenzene
b) 4-Chloronitrobenzene
c) 2,4-Dinitrochlorobenzene
d) 2,4,6-Trinitrochlorobenzene
Answer: d
22. Identify the catalyst in Friedel-Crafts acylation reaction.
a) Anhydrous FeCl3
b) Anhydrous AlCl3
c) NaNO2
d) Alcoholic KOH
Answer: b
23. What is the major product formed when chlorobenzene reacts with nitric acid in concentrated
sulphuric acid?
a) Nitrobenzene
b) 1-Chloro-2-nitrobenzene
c) 1-Chloro-3-nitrobenzene
d) 1-Chloro-4-nitrobenzene
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Answer: d
24. Which is the metal involved in Wurtz-Fittig reaction?
a) Iron
b) Magnesium
c) Aluminium
d) Sodium
Answer: d
25. Predict the minor product formed when chlorobenzene reacts with chloromethane in the presence of
anhydrous AlCl3?
a) Toluene
b) m-Chlorotoluene
c) o-Chlorotoluene
d) p-Chlorotoluene
Answer: c
26. What is the reason for iodoform to be used as an antiseptic?
a) Due to its unpleasant odour
b) Due to its melting point
c) Due to its solubility in alcohol
d) Due to the liberation of free iodine
Answer: d
26. Which of the following polyhalogen compounds in useful in extinguishing fires?
a) Dichloromethane
b) Trichloromethane
c) Triiodomethane
d) Tetrachloromethane
Answer: d
27. Which of the following is not a freon?
a) CCl3F
b) CCl2F2
c) CBr2F2
d) CClF3
Answer: c
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28. Freon 12 is manufactured from the Swarts reaction of which compound?
a) Dichloromethane
b) Trichloromethane
c) Tetrachloromethane
d) Dichlorodifluoromethane
Answer: c
29. Which of the following is not a characteristic of CHClF2?
a) Non-toxic
b) Non-flammable
c) Non-corrosive
d) Non-liquefiable
Answer: d
30. Which of the following is not a harmful effect of DDT?
a) It is non-biodegradable
b) Cannot be metabolized by animals
c) Highly toxic towards fish
d) Causes air pollution
Answer: d
31. Which of the following is not a use of carbon tetrachloride?
a) Manufacturing of refrigerants
b) Manufacturing of pharmaceuticals
c) Degreasing agent
d) Insecticide
Answer: d
32. Which of the following is not a use of methylene chloride?
a) Paint removal
b) Propellant in aerosols
c) Metal cleaning
d) Antiseptic
Answer: d
33. Which of the following is an effect of exposure to low levels of dichloromethane in the air?
a) Slightly impaired vision
b) Dizziness
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c) Nausea
d) Numbness in fingers
Answer: a
34. The oxidation of trichloromethane results in the formation of a poisonous gas called ________
a) carbon monoxide
b) carbonyl chloride
c) hydrogen sulphide
d) phosphine
Answer: b